Pump, Pipe or Faucet?

We are often asked to tweak the performance of web apps (our own and other people's). The first step is to figure out where the problem lies:

• The "pump" or originating server (either the web server, the data server, or both)
• The "pipe" or network connection (either the transport medium or routing hardware or both)
• The "faucet" or client computer (either the browser software or the client hardware)

There are many solutions for profiling server performance. It is pretty easy to randomly transfer large files across a network link to test the link's capacity. It is not hard to swap out client hardware for much faster (or slower) client hardware to see the effects of client hardware.

However, we were recently reminded that the complexity of the HTML the client is asked to render is often the culprit. We wrote a drastically simplified UI for a worrisomely slow application and were appalled at how much faster the resulting web page rendered, changing nothing else.

We take away two lessons from this exercise:

1. Tables within tables within tables may look great, but the resulting HTML can be very timeconsuming to render, even on a fast desktop. Use the HTML formatting with care

2. When faced with a poorly performing web app, an easy and useful test is to send the data with a minimum of formatting

Google Analytics

In order to improve our web site, we have started using Google Analytics to track traffic and web browser usage and such.

We tried out Google Analytics on a couple of personal web sites and were very impressed:

• no fee
• easy to install
• no impact on web site performance or appearance
• excellent statistics

Digital Voice Recorders

We have a problem: as consultants, we are often not at our desks. People mention things to us and ask us to do things while we are in the hall, the elevator or at someone else's desk. We just could not keep it all in our heads and often did not have our PDAs at the ready.

We also spend more time driving around and walking to and from meeting than we would like.

We recently tried carrying digital voice recorders to fill this note-taking gap and are quite pleased. We have some observations:

• get a VR which does uses an open standard to store its data
• battery life can be an issue
• you will want to access the files on your computer, so get a VR which looks like a USB flash drive to a computer and NOT a VR which requires special application software to access it

Google Analytics

In order to improve our web site, we have started using Google Analytics to track traffic and web browser usage and such.

We tried out Google Analytics on a couple of personal web sites and were very impressed:

• no fee
• easy to install
• no impact on web site performance or appearance
• excellent statistics

Ubuntu Desktop OK

It has been over a month now and our Unix developer is quite happy with his Ubuntu desktop. He can surf the web with Firefox, read his email with Thunderbird, get his internal IMs with GAIM, run Cisco-compatible VPN connections, use the built-in Terminal Services client with either VNC or Remote Destop. He can open the occasional MS-Office attachment with OpenOffice. He can even jam to his tunes with Banshee though he misses iTunes.

To his surprise, his monitor looks better under Ubuntu, though the fonts are slightly different and so he has had to fiddle a bit with web pages. He had figured that display was something that Microsoft would have been better at.

The only function which he has not been able to replace is a specialized hotsync conduit for his Palm Tungsten E.

All in all, he is very happy with the switch, though wishes that he had not let his desktop die, requiring an emergency conversion

WAP Replacement

One of our Wireless Access Points (WAP) went from flakey to dead yesterday. Luckily, a quick trip to Staples was all that we needed; it is amazing what qualifies as 'office supplies' these days.

In April of 2003 (!) we started an experiment: we wanted to see what Wireless networking could really do. So we set up an experimental WLAN with two segments: a wireless bridge from our office to a satellite location (a whopping 100 paces away) and a WLAN within the satellite location.

The bridge was to connect our experimental network with the network in the satellite location. The WLAN was to provide network connectivity within the satellite location.

Just to keep things interesting, the satellite location has a Mac, an appliance and the occaisional Windows box all trying to use the WLAN with varying degrees of success.

We quickly discovered what is now common knowledge:

• Wireless signal can really get around, so you have to secure WLANs
• 80211b or 80211g bridges (network-to-network connections) really cannot handle rain, wind or wet foliage
• Wireless support varies in quality from manufacturer to manufacturer
• Wireless networking is getting steadily better and better

How To Back Up VM Hosts?

Ok, so VMWare seems like an excellent solution for us. Now what? We back up the virtual hosts, that's what.

We back up over the network to disk. We use the NSLU2 from Linksys, but we use an Open Source Linux distribution to give us some functionality that the original firmware did not. That distribution is to be found at http://www.nslu2-linux.org/ and we highly recommend it.

We put all the virtual hosts (which appear to be single files on the physical host) on a drive on the XP box. We set up a separate NSLU2 just for this purpose and we back up the virtual hosts, in their entirety, with a combination of inhouse scripts and commercial software.

Ubuntu Server Experiment: Client/Server Development

Our chief windows developer wanted a home for a new client/server prototype. The product has an MS-Access front end and a MySQL back end. The developer wanted a spiffy new MySQL and a matching phpMyAdmin.

Our sys admin did not want to upgrade our main Linux database host just to accomodate this new project. At least not on a short enough time scale.

So we decided to kill two birds with one stone: try out VMWare as a Linux host and try out Ubuntu's server distribution. We let the windows developer create her own Linux server from scratch: she defined a virtual host for it, she installed Ubuntu 7.04 server on it and Ubuntu's LAMP (Linux Apache MySQL, Perl/PHP) server.

We were pleasantly surprised that she was able to do 99% of it herself and was up and running in a couple of hours. She now has a Linux back end for her project with which she can do as she pleases. The virtual client and the virtual server communicate over a virtual network, so they are not hogging our LAN bandwidth. HURRAY!

Ubuntu Desktop Experiment: Death of a Desktop

Argh! one of our windows desktops died today. We knew that it was in bad shape, but we had planned to phase it out and just waited too long.

Thank God we have a pretty good back up regimen, so very little was lost. But still.

The person whose desktop it was is a Unix developer who hated Windows anyway. Since we have heard lots of good things about the Linux distribution "Ubuntu", he has decided to take the retired Win98 host and repurpose it as an Ubuntu desktop. (We didn't want to let him nuke his old desktop, satisfying as that might have been. We try to keep retired disk drives around for a month or so in case there is something that we desparately need on them. After the cooling off period, we smash them with a hammer and take them to the dump.)

Physical Win98 Host Retired

We have shut off another physical computer as we are not able to support Access 97 on a virtual host. Our chief developer is down to one computer under her desk, but she's keeping the KVM switch as we see Vista bearing down upon us.

Still, the project is definitely a success: two physical hosts shutdown in three months.

VMWare Roll-out #2

We have deployed a second virtual host to replace the Windows 98 development platform. We initially tried to bring up a Windows 98 virtual machine, but not only was that a hassle (unsupported hardware) but we finally realized that it was a bad idea: Access 97 runs just fine under Windows 2000. So we brought up another Windows 2000 host and put Access 97 on it.

We looked into the VMWare solution for duplicating physical hosts, but it only works on Windows 2000 and up.

Physical W2K Host Retired

The initial roll-out was such a success that we have shut off the physical host. Our developer was able to support Access 2000 and use the VPN without being cut off from email and internal IM.

Onward to the next unwanted physical host!

VMWare Roll-out #1

We have too many computers in our lab. We use an outside porting lab for Unix projects, so we have a reasonable number of Unix machines, but our windows machines are out of control. We want special-purpose Windows development environments, but not the hassle, noise and heat of the army of machines that we have now.

It would also be nice to have a way for our windows people to use a VPN without being cut off from email and IM.

Our chief windows developer has a KVM switch with a Windows 98 box, a Windows 2000 box and a Windows XP box under her desk. This project's goal is to put everything on the XP box and retire the other two boxes.

In theory, virtualization offered us the perfect solution: have lots of special-purpose machines incarnated in the same machine. Easier to backup and access as well.

( Virtualization is the use of software to mimic hardware. The virtual host runs as an application on the physical host, but the software installed on the virtual host doesn't know the difference. Thus a large physical host can appear to be one or more less powerful hosts. )

We had heard alot about VMWare (www.vmware.com) and so we tried it out. Our initial tests with their freeware version were very promising, so we purchased their product and brought up a virtual windows 2000 box. We will be running the virtual and physical side-by-side to see if we can actually do without the physical host.